1. Field of the Invention
The present invention relates generally to a system and method for controlling a mobile terminal in a mobile communication system, and in particular, to a system and Method for remotely controlling a mobile terminal.
2. Description of the Related Art
In general, a mobile communication system provides a short message service (SMS) in which a user and transmit/receive a short message comprised of characters and numbers through a mobile terminal (or mobile station (MS)). A length of the message is restricted by system constraints. The SMS uses a data burst message based on a mobile communication protocol such as IS-95A, J-STD-008, IS-95B and 15-2000.
FIG. 1 illustrates a conventional network configuration for providing a short message service. Referring to FIG. 1, a BSC/BTS (Base Station Controller/Base station Transceiver System) 109 establishes a radio link to a mobile terminal (or mobile station (MS)) 111 within its service area (or coverage), and exchanges voice and data with the mobile terminal 111. Although the base station controller (BSC) generally controls a plurality of base stations, FIG. 1 shows that the base station controller controls only two base stations, for simplicity. In the following description, the BSC/BTS will be referred to as a “base station (BS)” for short. The base station 109 is connected to a mobile switching center (MSC) 107 connected to a public switched telephone network (PSTN) 113. The MSC 107 includes a visitor location register (VLR), and though not illustrated, is also connected to other MSCs. A home location register (HLR) 105 has subscriber authentication information and location information of the mobile terminals. A message center (MC) 103 provides additional services such as a voice mail service and the SMS service. Although the MC 103 is connected to the single MSC 107 in FIG. 1, it can also be connected to a plurality of MSCs. An SMS server 101 stores SMS messages to be transmitted to the mobile terminals. When there is an SMS message to be transmitted to the mobile terminal 111 or 117, the MC 103 either transmits the SMS message to the mobile terminal 111 through the HLR 105, or detects a location of the mobile terminal 117 and then transmits the SMS message along with an MAP (Mobile Application Part) message to the MSC 107 connected to the corresponding mobile terminal 117. The MSC 107 then transmits the SMS message to the mobile terminal 117 through the corresponding base station 115.
The mobile terminals should have an algorithm, called an “SMS message task”, for transmitting/receiving the SMS messages, and also have a specific key for accessing the SMS service in order to read a received SMS message or transmit an SMS message, and an icon indicating arrival of an SMS message. The SMS message task is commonly performed in association with an EEPROM (Electrically Erasable and Programmable Read Only Memory) database task for managing storage and deletion of data, and a diagnostic monitor task. Commonly, a search task is awakened (or activated) in response to Service Option 6, and then performs a corresponding operation.
FIG. 2 illustrates a structure of an SMS protocol stack among a mobile terminal, a base station and a message center in a general mobile communication system. An SMS message is formed based on an IS-95A, IS-95B, IS-2000 or J-STD-008 data burst message. The data burst message is transmitted over a paging channel and a forward traffic channel in a forward link, and transmitted over an access channel and a reverse traffic channel in a reverse link. During a call, the mobile communication system operates in a multiplex option (or mode) where data transmission is available during a voice call.
As illustrated in FIG. 2, the mobile terminal (BS) and the message center (MC) have the same layers. The layers include SMS teleservice layers (201 and 221), SMS transport layers (203 and 223), SMS relay layers (205 and 225), and link layers (207 and 227). The link layer 207 of the mobile terminal is based on IS-95A, while the link layer 227 of the MC is based on common channel signaling system No. 7. The base station (BS) has a structure for interfacing signals from the mobile terminal and the MC.
The associated layers of the mobile terminal and the MC have the same operations, so only the layers of the mobile terminal will be described for simplicity. As illustrated in FIG. 2, an SMS message is carried by a data burst message through the link layer 207. The relay layer 205 receives a message from the transport layer 203 and transmits the received message to a designated next relay point or a terminal point. Upon failure to transmit the message to the next relay point or the terminal point, the relay layer 205 creates an error indicator and transmits the error indicator to the transport layer 203. Further, the relay layer 205 transmits a received message to the transport layer 203. The relay layer 205 controls connection to the link layer 207 of IS-95A, IS-95B, IS-2000 or J-STD-008 protocol stack, in order to relay the message.
The transport layer 203 forms a terminal point for message exchange between the MC and the mobile terminal, and assembles a message by receiving bearer data from the teleservice layer 201. More specifically, the transport layer 203 assembles a transport layer message by receiving a message parameter from the teleservice layer 201, and transmits the assembled transport layer message to the relay layer 205 using a proper relay layer service primitive. In addition, upon receipt of an ACK (acknowledgment) in reply to the transmitted messages, the transport layer 203 informs the relay layer 205 of receipt of the ACK. However, upon receipt of an error report from the relay layer 205, the transport layer 203 provides the received error information to the teleservice layer 201. Further, the transport layer 203 receives an SMS message from the relay layer 205 and transmits the received SMS message to the teleservice layer 201. If authentication is enabled in the network, the transport layer 203 performs an authentication procedure specified in IS-637.
The SMS teleservice layer 201 supports a fundamental SMS function, using a standard subparameter of an SMS message data parameter from the SMS transport layer 203. When the mobile terminal transmits an SMS user ACK message, the SMS teleservice layer 201 transmits a destination address to the transport layer 203. When the MC has an SMS message to transmit to the mobile terminal and a reply option is set up, the SMS teleservice layer 201 provides this information to the user.
FIG. 3 illustrates a message format of each layer in a general SMS protocol stack. Referring to FIG. 3, a link layer 330 is comprised of a data bust message. The data burst message includes a message type field (MSG_TYPE) 331 indicting a type of the message, an ACK sequence field (ACQ_SEQ) 333, a message sequence field (MSG_SEQ) 335, a number field (NUM) 337, an SMS character field (CHARi) 339, and a reserved field 340. An SMS parameter is encapsulated in the character field 339, and the link layer 330 analyzes the character field 339 and transmits the analysis result to an upper layer.
A transport layer 310 is formed through a relay layer 320 based on the character field (CHARi) 339 of the data burst message serving as the link layer 330, as shown in FIG. 3. A transport layer message is comprised of an SMS message type field 311 indicating a type of the SMS message, a teleservice identifier field 313 indicating a voice mail service or a normal message service, an originating address field 315, a bearer reply option field 317 indicating a reply request, and a bearer data field 319. The bearer data field 319 is composed of a message of a teleservice layer 300. The teleservice layer message is comprised of a message identifier field 301, a user data field 303 filled with the contents of a received message, an MC time stamp field 305 indicating an MC time of the message, a priority indicator field 306, a privacy indicator field 307, an alert or delivery field 308 for alerting arrival of a message, and a language indicator field 309.
However, the mobile terminal supporting the SMS service becomes useless, when it is missing or not carried by the user. A future mobile terminal will store a great amount of important personal information in it. However, the user cannot remotely access the information stored in the mobile terminal. In other words, the user cannot access the information unless he or she carries the mobile terminal. Therefore, there is a demand for a method of remotely controlling the mobile terminal.